1. Field of the Invention
The present invention relates to a steering wheel in which a pad, to which an air bag apparatus is attached and which is an operating member for a horn switch, is attached to a supporting structure of a cored bar.
2. Description of the Related Art
FIGS. 10 and 11 show a general mounting structure of a steering wheel in a case in which a pad, to which an air bag apparatus is attached and which serves as an operating member for a horn switch, is provided at the central portion of a four-spoke type steering wheel. FIG. 10 is an elevational view of a steering wheel 10 in a state in which a pad is removed therefrom (shown by an imaginary line), and FIG. 11 is a cross-sectional view taken along line 11--11 of FIG. 10.
Brackets 12 are attached to the steering wheel 10, and a pad 14 shown by the imaginary line in FIG. 10 is attached to the brackets 12.
An air bag apparatus, not shown, is attached to the pad 14. The air bag apparatus is structured such that gas of an inflator operated by an acceleration sensor is rapidly injected into a folded bag body and expands the bag body. The frame body of the air bag apparatus is engaged with the brackets 12 by using screws or the like. The air bag apparatus is attached so that compressive and tensile load at the time of the unfolding of the air bag apparatus is supported by the cored bar 18 of the steering wheel 10 via the brackets 12
As illustrated in FIG. 10, when seen from the front of the steering wheel 10, the brackets 12 are substantially longitudinal plate-shaped members and are disposed left and right with the center of the steering wheel 10 therebetween. Further, through-holes 16 are formed at the free end portions of the bracket 12.
On the other hand, as illustrated in FIG. 11, at the cored bar 18 of the steering wheel 10, bosses 20 formed with a screw hole are disposed at four positions corresponding to the through-holes 16 of the bracket 12. A bolt 26, into which a bushing 22 and a washer 24 are incorporated, is inserted through the through-hole 16 of the bracket 12. Moreover, after a spring receiving member 28 and a compression coil spring 30 are temporarily assembled, the bolt 26 is clamped to the screw hole of the boss 20 such that the bracket 12 is attached to the cored bar 18.
At this time, the bracket 12 for the pad is urged by the spring 30 and abuts the reverse surface of a head 26A of the bolt 26. When the pad 14 is pressed, the bracket 12 can be displaced in the direction of the cored bar 18 while compressing the spring 30. A contact 32 of a horn switch is provided between the cored bar 18 and the bracket 12 for the pad. When the pad 14 is pressed, the horn sounds.
In a conventional steering wheel which is structured as described above, when the air bag apparatus operates and the bag body is rapidly expanded by the gas injected from the inflator, from the air bag apparatus to the steering wheel 10, at first a large impact load is applied in the direction opposite the vehicle operator's direction, i.e., the direction of arrow A in FIG. 11 and, at the next moment, a large impact load is applied in the direction opposite the direction of arrow A. Namely, besides the large bending load applied to the bracket 12 which supports the air bag apparatus in the direction of arrow A and the direction opposite the direction of arrow A, a large compressive and tensile load is applied to the members such as the bolt 26 and the boss 20 which engage the bracket 12 with the cored bar 18.
In order to be able to resist the large load, the size or thickness of each of the members such as the cored bar 18, the bracket 12, the bolt 26, and the boss 20 is increased so as to enhance the strength of each of the members. Therefore, a drawback arises in that the members become large, heavy, and expensive.